Patent GB-354405-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone exchange systems
IPC: H04Q3/42
Filed: 1930-05-13
Abstract: 354,405. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. and WRIGHT, E. P. G., Columbia House, Aldwych, London. May 13, 1930, No. 14707. [Class 40 (iv).] Routing digits are sent out by register-senders under the control of common translating switches of which a separate bank is used for each routing number required. The translating switches may also transmit a zone-metering indication to the register-sender which subsequently transfers it to a repeater in the talking circuit. The invention is described with reference to a byepath system similar to that described in Specification 346,368 in which the first byepath 1B is operated by the first code digit, and a switch R3 in the second byepath 2B is set in accordance with the second and third code digits, a register-sender R only being used under certain circumstances e.g. for tandem calls. The appropriate translating switch TM and the particular bank of that switch are selected over wipers rm31, rm32, Fig. 3, of the switch R3. Transmission of routing digits. Starting relay S in the register-sender, Fig. 2, connects up the magnet FM of the associated finder and when the casing second byepath is reached relay T operates and energizes relay E. When the byepath has selected an outlet in the wanted direction, relay H operates over wiper fm2 and connects relay F over wipers fm5, rm31 to relay TA, Fig. 3. When the translating switch is in its normal position relay TA operates over wiper tm1 and on the next separation of springs TS (synchronous with spring LS, MS, Fig. 2) relay TB operates and connects springs TS to magnet TM causing the switch TM to start stepping. Relay F operating in series with TA locks up relay G and on the first step of switch TM the release of relay F connects relay A over wipers fm6, rm32 to wiper tm2 the bank of which is wired to send first a zone-metering indication and then a 3-digit routing number. The stepping of the switch TM takes place uniformly over the whole wired portion of its bank and the necessary pause between digits is provided by groups. of blank terminals between the groups of multipled terminals. The first multipled group causes relay A to connect springs MS to magnet SM for a time sufficient to step wipers sm1, sm2, sm3 an equivalent number of steps and when relay A releases, zone-metering relays O, M, N, or M+N, are operated in accordance with the position of wiper sm3. (Relay 0 indicates a call to an operator and by releasing relay E causes the register to release without receiving any numerical digits). Relay L also operates in parallel, removing a short-circuit from springs LS and completing a circuit over wiper sm2 for moving switch SM to position 6. When wiper tm2 reaches the next multipled group of terminals relay A operates to remove a further short-circuit from springs LS which transmit a corresponding number of impulses over a loop including wipers fm3, fm4. Two further routing digits are similarly transmitted after which relav TB releases and switch TM returns to normal over its own interrupter contacts. Relay F then re-operates energizing relay Z and driving switch SM to position 8. Numerical digits. The numerical digits are repeated from the second byepath over wiper fm9 to switch magnet NM in series with relay C which energizes relay K. At the end of the first digit between the relapse of relays C, K, storage relays XA . . XD are operated in an appropriate combination and on the relapse of relay K the switch NM advances to its next home position. The second and third digits are similarly recorded on relay sets and the fourth digit remains registered on the switch banks, relay K remaining operated in the latter case over wiper nm5. When relay Z operates as referred to in the preceding paragraph it connects a polarized relay D in the outgoing loop. If the distant exchange is not ready to receive impulses relay D operates and holds Z. If however relay D does not operate relay Z releases and connects springs MS to magnet SM. Relay A operates over wiper sm2 and impulses are sent out by springs LS until wiper sm3 reaches a terminal marked in accordance with the setting of thousands relays XA .. XD. Relay Z then operates to prevent further impulsing and is locked by relay A until the starting position for the next digit is reached. Relay A then releases followed by relay Z provided that the hundreds digit has been recorded. The retransmission of the remaining digits takes place in a similar manner after which relay O operates over wiper sm2 releasing relay E. Earth is thereby connected over wiper fm8 to cause the second byepath to switch through the calling subscriber's loop to the outgoing repeater. Release of register-sender ; zone-metering control. The removal of the feed from the loop over wipers fm3, fm4 releases relay H whereby earth is connected to one or other or both of these wipers in accordance with the setting referred to above of relays O, M, N, thus transferring the zonemetering indication to the outgoing repeater. Relay Z which had been operated over wiper sm3 is released and the switch SM takes two steps after which Z operates again over sm3. Relay E now operates to remove holding earth for the byepath from wiper fm2 with the result that relay T is released completing restoring circuits for switches XM, SM. Statistical metering. Relays EX, Fig. 3, control traffic meters to record the number of calls to each exchange.